Kangaroo Walker
A small autonomous walker that mimics the pentapedal gait of a kangaroo and reliably traverses rough paving stone. Powered by a 3V battery pack delivering 2.6V to a single Tamiya 6 Speed H. E. motor, it successfully crossed Meyer Circle, our test site. With a transmission ratio of 196.7:1 and a belt system powering five 4-bar linkages representing forelimbs, hind limbs, and a tail, it accurately recreated pentapedal locomotion. Traveling at 11.2 cm/s, it overcame wet and windy conditions and maintained a straight course without intervention. Force plate analysis demonstrated that its force and power generation were proportional to those of a real kangaroo.
Our kangaroo walker’s frame shape, limb placement, limb curves, and limb synchronization were all designed to closely mimic that of a biological kangaroo. The kangaroo walker moved most effectively when these limbs were synchronized in a biomimetic manner. As a result, the force and power generation sequence of our kangaroo walker limbs in the vertical and fore-aft directions were highly biomimetic. For a more detailed description of the design process regarding this project — read the full report.
Shaft Crawler
A small lego crawler that can ascend and descend a steep narrow shaft similar to those found inside the Egyptian pyramids. Our crawler successfully traversed the shaft in an efficient manner while carrying a bolt to simulate drilling capacity. After depressing a bumper switch at the top to turn on a light, it returned smoothly down the shaft. We prototyped various designs to determine a suitable gear ratio, driving wheel location, and stabilizing mechanisms to balance the friction and rolling forces. Original design personally assembled by hand.
Our final design involved a two-sided folding frame. It used a pair of rubber bands to exert the necessary normal force on the shaft walls to maintain a suitable friction force that could allow it to descend and ascend without falling. Stretched to different lengths, these rubber bands provided a crucial moment on the crawler that predisposed it to climb in rather than out of the shaft.
We used a gear ratio of 125:1 and ran the motor at 6V in ascent and 3V in descent to improve efficiency. On test day we used 13.99J in ascent and 1.40J in descent for a total of 15.39J, which was significantly below the 60J limit. We calculated that our motor was 53.0% efficient, our transmission was 34.7% efficient, and that our wheels were 89.1% efficient for a total experimental efficiency of 16.4%. To further reduce energy consumption and improve efficiency we could reduce the crawler weight. For a more detailed description of the design process regarding this project — read the full report.
Golfer
A golf putter that can consistently putt golf balls at reasonably high speeds.
We designed a linkage system that we lasercut and mounted to a duron frame provided by the class instructors.
For a more detailed description of the design process regarding this project — read the full report.